This invention relates to a walking beam compressor, and more particularly to a walking beam compressor which has a rod collar assembly to minimize wear of the compressor rod seals. The compressor also has an improved piston rod seal assembly and an improved piston assembly.
Typically, a pumping unit for an oil well includes a compressor mounted between the walking beam and the Samson post or other stationary part of the pumping unit. A chronic problem associated with walking beam compressors is that rod side loading often occurs which results in excessive wear of the rod seals in the rod seal assembly of the compressor which engage the piston rod as it moves up and down. Various attempts have been made to overcome the problems associated with side loading. For example, Mayland U.S. Pat. No. 5,290,156 discloses the use of spherical bearings at each of the connecting ends of the compressor to allow universal movement in response to any lateral displacement or side loading. Studinger U.S. Pat. No. 4,345,744 uses spherical bearings at each of the connecting ends of the compressor to allow non-restricted, omni-directional movement at both connecting ends. McCoy U.S. Pat. No. 4,530,646 has a swivel connector at opposite ends for connecting the compressor to the walking beam and the Samson post to accommodate side loading. McClung U.S. Pat. No. 3,655,301 has knuckle joints and a buckle adjuster to minimize side loading. While these devices are satisfactory for their intended purpose, no attempt has been made to modify the compressor structure to minimize side loads thereon.
The present invention is directed to a walking beam compressor having a rod collar assembly attached to the top cap of the compressor cylinder and has bearings which absorb side loading imposed on the piston rod. The rod collar assembly includes a sleeve which extends upwardly from the top cap and supports a pair of stacked inserts which form a recess to support a bearing through which the piston rod extends.
Conveniently, the top cap includes a top cap assembly which supports a pair of vertically stacked seals sandwiched between three inserts. The inserts are housed in a counterbore formed in the top cap and covered by an insert cap thereabove. Each of the upper and lower inserts houses a wear ring so that one wear ring is above the seals and the other wear ring is below the seals.
The piston is divided into an upper section and a lower section to facilitate the mounting of a peripheral seal at the mating surfaces of these sections. The peripheral edge of each section has a recess for receiving a wear ring. A structure is provided to facilitate separating the upper and lower sections during disassembly.
Additional advantages of this invention will become apparent from the description which follows, taken in conjunction with the accompanying drawings.